A conventional radio access network (RAN) is configured to provide connectivity between User Equipment (UE) such as mobile communication devices and a packet data network that provides end-to-end communications services. FIG. 1 schematically illustrates a conventional radio access network (RAN). As may be seen in FIG. 1, the RAN 2 comprises a plurality of radio Access Points (APs) 4 that are connected to one or more Packet Data Network Gateways (PGWs) 6 through a wired network 8. In some cases, the wired network 8 may rely on legacy copper cables for connections between nodes. However, increasingly, connections between nodes of the wired network 8 are set up through optical fiber links. The APs 4 include radio transceiver equipment for maintaining wireless connections with the UEs 10, and signal routing equipment for forwarding signals through the wired network 8 to the PGWs 6. Each PGW 6 provides a link between the RAN 2 and the packet data network 12, and so enables traffic flows between the packet data network 12 and UEs 10. It is common to refer to the wired portion of the RAN 2, including the wired network 8, PGWs 6, and the wired links between the APs 4 and the wired network 8 as the “backhaul” network, and to refer to the wireless portion of the of the RAN 2, including the UEs 10, radio equipment of the APs 4, and the wireless links between the UEs 10 and the APs 4 as the Wireless Access network.
Typically, these traffic flows are associated with specific services of the packet data network 12 and/or the RAN 2. As is known in the art, a service of the packet data network 12 will involve a downlink traffic flow from one or more of the PGWs 6 to a UE 10, and an uplink traffic flow from the UE 10 to the involved PGWs 6. Similarly, a service of the RAN will involve a downlink traffic flow from one or more servers 14 of the wired network 8 to a UE 10, and an uplink traffic flow from the UE 10 to the involved servers 14. In both cases, optimization of the uplink traffic flows involves optimization of both the wireless link between the UE 10 and one or more host APs 4, and the wired links through the wired network 8 from these host APs 4 to the involved PGWs 6 or servers 14 of the wired network 8.
Optimization of the wireless link typically implies scheduling data transmission from the UE 10 to its host AP(s) 4 according to an objective which usually is a function of the UEs' transmission rates.
Optimization of the wired link through the wired network 8 typically implies finding an optimal routing through the wired network 8 from the APs 4 to the appropriate servers 14 or PGW(s) 6. In some cases, the traffic flows associated with a given network service must be routed through a specific user plane function path. A user plane function path is a sequence of one or more function nodes that the traffic flows must go through. For example, a given service may be associated with one or more Service Gateway (SGW) nodes within the RAN, and traffic flows associated with that service must be routed to those SGWs. Additionally, some services have specific quality of service (QoS) requirements that specify limits on traffic latency, for example. The routing algorithm must accommodate these requirements.
Typically, scheduling and routing optimization are treated as separate problems that are solved using independent algorithms. While this approach is efficient, and leads to optimization of each of the wireless and wired links, in some cases the combined path including both the wireless and wired links is still sub-optimal.
Accordingly, it would be desirable to be able to efficiently optimize the combined wireless and wired paths from the UE